In many electronic systems, large amounts of data are often transferred between components in parallel or serial format. Some components across which the data are to be transferred, for example, packet switching devices, can be extremely complex. Oftentimes, because of limitations such as pin count limits, such devices can be more efficiently implemented as multiple relatively small devices that operate in parallel, rather than as a single large device. Consequently, to accommodate this implementation, packets of data can be split into multiple portions, each of which is transferred along a separate parallel processing path to one of the devices. At the output of the devices, the portions of the data packets are reassembled or grouped into the original data packet for further processing.
There are many sources of error in reassembling or grouping the data packet portions into the original data packet. For example, in many systems, it is desirable and/or required that the individual data paths operate asynchronously with respect to each other and independently of each other and also that the grouping device be located a substantial distance from the individual data paths. These factors can result in a system implementation in which there is no real-time communication between the individual processing paths and the grouping device. With no inherent time relationship between portions of the data packets arriving at the grouping device that would identify the portions as belonging together in the same data packet, data packets may be formed by grouping portions that do not belong together. Other factors may also contribute to the possibility of grouping unrelated portions of data packets. For example, errors such as parity errors in one or more of the individual paths, which can be caused by such factors as noise, may result in the loss of a portion of a packet. At the grouping device, it is important to discover such errors to prevent the grouping device from inadvertently replacing the lost portion with a portion of another packet and then incorrectly reassembling the packet.